Charles l



(No Model.) r

C. L. HART.

STAMPING PRESS.

No. 402,668. Patented May 7, 1889.

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UNITED STATES ATENT OFFICE.

CHARLES L. HART, OF BROOKLYN, NEW YORK, ASSIGNOR TO THE E. W. BLISS COMPANY, OF SAME PLACE.

STAM PING-PRESS.

SPECIFICATION forming part of Letters Patent No. 402,668, dated May 7, 1889.

Serial No. 301,830. (No model.)

To all whom it may concern.-

Be it known that I, CHARLES L. HART, a citizen of the United States, residing in Brook lyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Stamping-Presses, of which .the following is a specification.

This invention relates to presses for stamping out sheet metal or other material and shaping or forming it by pressure between dies, and to other presses of analogous character. In presses of this type, wherein the sheet metal or blank is drawn over a plug or projection on one die and into a cavity in the other, it is liable to be wedged fast within said cavity, so that it is difficult to remove it in order to enable the next stamping operation to be performed.

My invention has for its object to provide a simple and practicable means for expelling the work from the cavity of the female die in presses where such die is carried by the movable head or slide of the press. To this end I provide the female die with aknockout-pad or plunger, as heretofore, and which is usually formed with a stem projecting through the die, and I arrange a knockout-lever to project into the path of some part of said plunger, (preferably its stem,) a su-itable cavity being constructed, if necessary, in the head of the press to admit this lever. The lever, which may move down with the head of the press, is stopped in itsupward movement by striking a fixed stop, preferablya stop-screw, to enable it to be adjusted. The stoppage of the lever against this screw in turn stops the plunger, and the continued upward movement of the head expels the-struck-up blank or work from the die.. l

Figure l of the accompanying drawings is a side elevation of a stamping-press embodying my invention, the View being partly in vertical mid-section cut in the plane of the line l l in Fig. `2. Fig. 2 is a transverse section thereof cut in the plane of the line 2 2 in Eig. l. Fig. 3 is a fragmentary section cut in the same plane as Fig. l and showing the moving parts in a different position. Eig. et is afragmentary section similar to Fig. 3 and showing a modied construction.

The particular type of press shown in the drawings is known as an adjustable press,

or one the body of which can be tilted back from the vertical to any desired angle. My invention, however, is not limited in its apf plication to this style of press.

In Fig. l, A designates the base-frame or legs of the press; B, the press-frame; O, the crank-shaft; D, the flywheel; F, the presshead or slide, sometimes called the mandrel, and G the pitman connecting the crank C to the head F and adjustable in length by means of a right and left threaded sleeve, a., all as usual. H is the upper die J the lower die; K, the lower die bed-plate orbolster, and L the bed or table of the press. In 4the particular press here shown the dies are constructed to cut or punch out a disk or blank from a sheet of metal, and then by a continuation of the movement to draw this blank into the form of a cup. Such presses are used for stamping the covers of tin pails, blackingboxes, and various other articles. The upper die, H, is formed with a cutting or shearing edge, c, which enters within the shearing-edge d of the lower die, J, and cuts out the blank. The blank vis then held between the blankholding surface c of the upper die and the blank-holding ring f, which is seated in the lower die and movable up and down therein, resting on pins g g, which pass down through the die and are fixed to a disk, h, resting on a rubber spring, i, all as shown in Fig. 3. The ring f thus yields to the downward movement of the die H, and the blank is drawn overthe former or plug j within the die J. I/Vithin the cavity in the female die H, into which the blank is forced while being drawn over this plug, is arranged a piston or plunger, M, called a pad or a knockout-plunger. In a press which, in addition to drawing the blank, embosses it with letters or other designs the lower surface of this plunger M isY engraved to form an embossing-die, the top of the plug j forming the opposite embossing die. This plunger M is usually constructed with a stem, m, called the pad-stem;7 and which projects up through the die H. Means are provided for arresting the ascent of this plunger' or its stem in order to expel the iinished blank from the cavity in the female die.

As thus far described the press is of the usual construction.

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According to my invention I provide a knockout-lever, N, f ulcrumed on a pivotal stud, n, and arranged with its end n projecting over the top of the pad-stem m, or otherwise, into the path of some part of the plunger M. This leverv is preferably arranged in the rear of the dies, and the press-head F is formed with a recess, k, extending into it from the rear, in order to admit the end n of the lever. In the preferred construction shown in Figs. 1, 2, and 3 the lever N is pivoted near its middle `on a stud or boss, p, Fig. 2, cast as a projection from the interior of the pressframe B. The tail of the lever N stands over a fixed stop, P, which forms part of or is fixed to the press-frame B. This stop is preferably a screw fastened in the frame and secured by a jam-nut in order that it may be adjusted to different positions.

The adjustment of this stop is such that during the upstroke of the press -head F the lever N, resting against the stop, has its end n. in such position as to be encountered by the stem m before the completion of the upstroke, and preferably a distance below the extreme upstroke equal at least to the depth of the draw of the blank or work which the press is operating upon. Ilence during the upstroke the plunger M is arrested by contact of its stem on. with the lever N, and its further movement is prevented while the head continues to rise, so that the die II is drawn back, and the blank, being stopped against the plunger, is expelled.

Preferably a spring, s, is applied in order to hold the lever M pressed against the stop P and thereby prevent rattling. lVhen the press-head F is adjusted well up, (as it is in using dies H and .I of considerable depth,) the lever N may, if the cavity k is of sufficient height, reniain stationary, being held continually against the stop P by the tension of the spring s. If, on the contrary, the head F is adjusted lower down, or the cavity k is made of less height, the lever N will be tilted at each downstroke of the head by the roof of the cavity striking against its end n and lifting its tail off from the stop P, as shown in Fie. l.

lthough it is preferable that the lever N shall be fulcrunied on a fixed pivot, n, yet this construction is by no means essential. Fig. et shows a construction in which the pivot n isniovable, being carried by the presshead F through the medium of an intervening rigid arm, p, projecting from the rear of the head. In this case the stop P will be arranged between the fulerum n and the free end n', being preferably a screw screwing into the cross-tie bar q, which unites the opposite halves or sides of the frame B together. This stop is so arranged or adjusted as to be encountered by the lever N shortly before the end of the upstroke of the presshead,whereby the plunger M is arrested, and by rea-son of the rocking of the lever IT against the stationary stop P by the continued upward movement of its fulcrum-point n the plunger M is forced downwardly instead of being held stationary, as in the construction iirst described.

My improved knockout device is arranged wholly in the rear side of the press, where it is out of the way, is not visible from the front, is in a position where it cannot interfere with the operation or adjustment of the press, and is readily adjustable to different conditions of work.

I claim as my invention the following-defined novel features and combinations, substantiall y as hereinbefore specified, namely:

l. The combination, with the movable head of a stamping-press and its die and knockout-plunger, of a knockout-lever arranged to project into the path of said plunger and a stop against which said lever abuts, whereby during the upstroke of the head the lever stops the plunger and the continued upward movement of the head expels the work from the die.

2. The combination, with the movable head of a stamping-press and its die and knockout plunger, of a knockout-lever arranged to project into the path of said plunger and an adjustable stop-screw against which said lever abuts.

3. The combination, with the movable head of a stamping-press andits die and knockout plunger, of a knockout-lever arranged to project into the path of said plunger, mounted to turn on a fixed fulcrum, and formed with a tail projecting to the opposite side of said fulcrum, and a stop against which said lever abuts.

4. The combination, with the movable head of a stamping-press and its die and knockout-plunger, of a knockout-lever arranged to project into the path of said plunger, a stop against which said lever abuts, and a spring arranged to exert a tension against said lever to prevent rattling.

5. The combination, with the movable head of a stamping-press and its die and knockoutplunger, the said head formed with a cavity in its rear, of a knockout-lever with its end projecting within said cavity into the path of said plunger and a stop against which said lever abuts.

G. The combination, with the frame of a stamping-press and with its movable head, die, and knockout-plunger, of a knockoutlever arranged behind the head and within the frame, with its end projecting forwardly and standing in the path of said plunger, and a stop against which said lever abuts in order to arrest the plunger.

In Witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

CHARLES L. HART.

lVitnesses:

MAURICE TrLroN, F. C. B. PAGE.

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